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      07-26-2014, 08:42 PM   #1
ddk632
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Video of BMW engineer explaining i8 driving modes

Interesting and informative video, looks like from LA press launch, with a BMW engineer going over the multiple drive modes.

He also goes into some detail about the 2nd additional electric motor, and its 3 functions to the car. Worth a watch.

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      07-27-2014, 07:32 AM   #2
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This was the first time I heard how one can change between auto shifting and manual shifting in Sport mode. As I understood it, after putting the shift lever into Sport mode the car is in auto shift. If one then uses the paddle shifters, the car will go into manual shifting and remain there until one moves the shift lever back to Drive and then back to Sport, at which point it will return to auto shifting. Does that sound right?
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      07-27-2014, 08:31 AM   #3
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I don't think the engineer gave all the full details.

The Owner's Manual states that in manual shift mode, the transmission will automatically upshift if the engine temps are too high or to reach maximum engine speed.

It also says that the car will revert to automatic mode after a period of shifting inactivity in manual shift mode.

So it will stay manual as long as you are continually shifting, for example in canyon driving, but it you're accelerating towards max revs, it will upshift rather than keep the engine pegged at max revs in a lower gear.
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      07-27-2014, 06:40 PM   #4
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Almost every paddle shift car I've driven will also go back to auto mode if you hold the shift-up paddle of a few seconds.
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      07-27-2014, 08:14 PM   #5
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I didn't see anything in the i8 manual about that.

Will try in my X6M; never thought about it. I rarely use the paddles, preferring instead to manually shift with the shifter. I am old-school like that. I'll try it.

-----------------

On another note, I've been reading through some literature posted on another BMW forum and learned some interesting bits about the 2nd electric motor, which seems to not be talked about very much.

It produces 37 ft-lb of torque for "torque fill" while the ICE is running.

Most specs for the i8 seem to mention specs of 357hp and 420 ft-lbs of torque; looking on the bmw.com spec sheet for the i8, there is no "system output" figure for torque. There are individual numbers for the electric motor and the ICE, but those numbers do not include the output of this 2nd electric motor, known as the
high-voltage-starter-motor-generator, which also replaces a conventional starter motor, and supplies the electrical system in the vehicle.

So it is evident that when the numbers are reported, they just add up the torque output of the two main motors and report it as 420 ft-lb.

The max system output stated in the tech manual document is actually stated as 457 ft-lb.

184 from electric motor
236 from ICE
37 from starter motor generator
457 total ft-lb torque

Thought that was a nice bit of info.

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File Type: pdf 03_I12 Powertrain.pdf (2.75 MB, 12617 views)
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      07-27-2014, 10:12 PM   #6
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One interesting factoid under the section on the main electric motor is that it can only provide its maximum power for 5 seconds in order to avoid the risk of overheating components.
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      07-28-2014, 11:21 AM   #7
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I just joined the forum, but cannot post a new thread. Any idea why please?
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      07-28-2014, 12:00 PM   #8
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Quote:
Originally Posted by JasH View Post
I just joined the forum, but cannot post a new thread. Any idea why please?
No idea; as far as I know, there is no restriction on posting a new thread for a new member. If you're on the phone app, try the computer instead. Sorry wish I could be more helpful.
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      07-28-2014, 04:14 PM   #9
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Thanks, I am using a PC though. Can reply but not start a thread Probably something the mods need to permit me to do.


UPDATE: now fixed, thread started My test drive of the i8

Last edited by JasH; 07-28-2014 at 04:16 PM.. Reason: UPDATE
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      03-12-2018, 10:50 AM   #10
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i8 i12 manual

Hi sir ,
do you have another part of the i12 pdf
I'm looking for 06_i12 high-voltage commonents and etc.

thank you , best regards

Robert


Quote:
Originally Posted by ddk632 View Post
I didn't see anything in the i8 manual about that.

Will try in my X6M; never thought about it. I rarely use the paddles, preferring instead to manually shift with the shifter. I am old-school like that. I'll try it.

-----------------

On another note, I've been reading through some literature posted on another BMW forum and learned some interesting bits about the 2nd electric motor, which seems to not be talked about very much.

It produces 37 ft-lb of torque for "torque fill" while the ICE is running.

Most specs for the i8 seem to mention specs of 357hp and 420 ft-lbs of torque; looking on the bmw.com spec sheet for the i8, there is no "system output" figure for torque. There are individual numbers for the electric motor and the ICE, but those numbers do not include the output of this 2nd electric motor, known as the
high-voltage-starter-motor-generator, which also replaces a conventional starter motor, and supplies the electrical system in the vehicle.

So it is evident that when the numbers are reported, they just add up the torque output of the two main motors and report it as 420 ft-lb.

The max system output stated in the tech manual document is actually stated as 457 ft-lb.

184 from electric motor
236 from ICE
37 from starter motor generator
457 total ft-lb torque

Thought that was a nice bit of info.

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      03-12-2018, 06:16 PM   #11
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Wow, serious thread resurrection

btw, engineer omitted to mention holding the paddle in sports mode, to go back to auto-shifting.

I learned ONE new thing though. That e-drive itself has a second mode, eco-pro. I guess that's one way to reach 20 miles or so, electrically.
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      03-13-2018, 05:25 AM   #12
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New(ish) Owner - great info

Good to have some explanation in the powertrain pdf file. Had mine since December 17 but due to poor weather and having an X3 as well I have not really used it that much.

What I found interesting was that it charges the battery whilst driving in Eco Pro and Comfort Modes but seems to stop at about 15% charge. Obviously you get regeneration as well but I thought charging was in sport mode only so you do learn something every day.

I got the i8 out of curiosity on the technology integration rather than its ultimate performance so this kind of stuff is great to find amongst the lease takeover threads.

Cheers FF.

Last edited by FrequentFlyer; 03-13-2018 at 05:52 AM..
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      03-13-2018, 06:00 AM   #13
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thanks for sharing very interesting
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      03-13-2018, 02:37 PM   #14
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Torque fill electric motor energy source

It was interesting to review this again. Going back through the earlier posts dating back to 2014, I saw where I made a couple of those posts. This was while I was waiting for my car to come in (as we all were back then). So I obtained this great understanding of the car all to no avail back then, as I had to cancel my order due to a medical emergency. But, the good news is that that knowledge will not go to waste since I am finally getting my i8 (2019 coupe) in another month.

There was one question in the video that I don't think the BMW engineer answered. One of the guys asked where the small, torque fill electric motor gets its energy. Is it driven by the ICE? It would seem odd if it were to get energy from the high voltage battery, since it is the source for charging that battery. Anybody know the answer (I don't)?
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      03-20-2018, 03:36 PM   #15
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Quote:
Originally Posted by drlonline View Post
One of the guys asked where the small, torque fill electric motor gets its energy. Is it driven by the ICE? It would seem odd if it were to get energy from the high voltage battery, since it is the source for charging that battery. Anybody know the answer (I don't)?

Small motor gets electricity from normal high voltage battery when providing torque fill.

When ICE is charging it (surplus torque), then from the ICE and sends it to HV battery.
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      03-25-2018, 05:02 PM   #16
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Quote:
Originally Posted by JasH View Post
Small motor gets electricity from normal high voltage battery when providing torque fill.

When ICE is charging it (surplus torque), then from the ICE and sends it to HV battery.
Another way of saying “surplus torque” is: the starter-motor-generator is physically connected to and spins with the drivetrain. Acting as a generator, it created electricity via induction, which creates a load on the drivetrain. I.e., it takes a bit of power to spin it. That’s why charging your battery in sports mode will increase your fuel consumption - obviously, since energy can’t be created out of thin ain.
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      03-25-2018, 05:18 PM   #17
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What I thought was interestring was how he explained that the electronics match the torques between the front and the rear drivetrains. For obvious reasons, as I think about it.

Makes me wonder how broad that band is in which the electronics are effective and what that means for tuning the ICE.

Although it sounds like it mainly a problem of torque fill on low ICE RPMs, which is where the starter-motor-generator kicks in. So maybe more ICE torque just reduces that problem and doesn’t actually create any others?
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      03-26-2018, 12:24 PM   #18
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Quote:
Originally Posted by Aye-eight View Post
Another way of saying “surplus torque” is: the starter-motor-generator is physically connected to and spins with the drivetrain. Acting as a generator, it created electricity via induction, which creates a load on the drivetrain. I.e., it takes a bit of power to spin it. That’s why charging your battery in sports mode will increase your fuel consumption - obviously, since energy can’t be created out of thin ain.
That's true, under partial load, but there is another aspect to this.

It really is surplus torque, because if the throttle is 100%, then the small motor will not provide resistance. Depending on power needs at the moment, it may even provide additional torque to the ICE.
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      03-26-2018, 06:22 PM   #19
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Quote:
Originally Posted by JasH View Post
That's true, under partial load, but there is another aspect to this.

It really is surplus torque, because if the throttle is 100%, then the small motor will not provide resistance. Depending on power needs at the moment, it may even provide additional torque to the ICE.
True. But then it can’t charge the battery.
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      03-27-2018, 11:50 AM   #20
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Quote:
Originally Posted by Aye-eight View Post
True. But then it can’t charge the battery.
Absolutely.

It is one or the other. As you say, can't create energy from nothing.




....apart from in my car of course....I opted for the Flux Capacitor option
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